Eumuroida
Encyclopedia
Eumuroida is a clade
defined in 2004 (Steppan et al.) to describe a group of muroid
rodent
s. The clade
is not defined in the standard taxonomic hierarchy, but it is between superfamily
and family
.
The Eumuroida is technically defined as the clade
including all organisms descended from the most recent common ancestor of the Calomyscidae, Nesomyidae
, Cricetidae
, and Muridae
. It specifically excludes the fossorial
forms of mouse-like rodents in the family Spalacidae
. It is yet to be determined if the Platacanthomyidae belong to the Eumuroida, but Norris et al. (2004) suggested they do not because of subtle features in the skull
.
Norris et al. (2004) noted that two characters can be used to define the Eumuroida: the infraorbital foramen
is V-shaped and extends to the roof of the palate
, and the incisive foramina
are medium to large in size. The zygomatic plate
is at least moderately developed in this group, producing the V shape. The common ancestor to the Eumuroida were probably not specialized as burrowing animals, whereas the spalacid ancestor may have been.
Jansa and Weksler (2004) noted that the Eumuroid ancestor likely had hamster
-like (cricetid
) molar
s as opposed to mouse
-like molars (murid
). Essentially, the occlusal surface of the molars probably had two rows of cusps (cricetid) instead of three (murid).
Early fossil
muroids
such as cricetodontines represent a possible ancestor
to the Eumuroida. These rodent
s have the cricetid tooth, hence the name: cricetus = hamster
+ dont = tooth
. The presence of these fossils in Eurasia
is parsimonious
, because most families of eumuroids (except the Nesomyidae) have representatives in Asia. Steppan et al. (2004) suggested that the most recent common ancestor of the Eumuroida lived around the transition between the Oligocene
and Miocene
. This date only slightly precedes the first appearance of cricetodontines.
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
defined in 2004 (Steppan et al.) to describe a group of muroid
Muroidea
Muroidea is a large superfamily of rodents. It includes hamsters, gerbils, true mice and rats, and many other relatives. They occupy a vast variety of habitats on every continent except Antarctica. Some authorities have placed all members of this group into a single family, Muridae, due to...
rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s. The clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
is not defined in the standard taxonomic hierarchy, but it is between superfamily
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
and family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
.
The Eumuroida is technically defined as the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
including all organisms descended from the most recent common ancestor of the Calomyscidae, Nesomyidae
Nesomyidae
Nesomyidae is a family of African rodents in the large and complex superfamily Muroidea. It includes several subfamilies, all of which are native to either continental Africa or to Madagascar...
, Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
, and Muridae
Muridae
Muridae is the largest family of mammals. It contains over 600 species found naturally throughout Eurasia, Africa, and Australia. They have been introduced worldwide. The group includes true mice and rats, gerbils, and relatives....
. It specifically excludes the fossorial
Fossorial
A fossorial organism is one that is adapted to digging and life underground such as the badger, the naked mole rat, and the mole salamanders Ambystomatidae...
forms of mouse-like rodents in the family Spalacidae
Spalacidae
The Spalacidae, or spalacids are a family of rodents in the large and complex superfamily Muroidea. They are native to eastern Asia, the Horn of Africa, the Middle East, and south-eastern Europe. It includes the blind mole rats, bamboo rats, root rats, and zokors...
. It is yet to be determined if the Platacanthomyidae belong to the Eumuroida, but Norris et al. (2004) suggested they do not because of subtle features in the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
.
Norris et al. (2004) noted that two characters can be used to define the Eumuroida: the infraorbital foramen
Infraorbital foramen
Above the canine fossa is the infraorbital foramen, the end of the infraorbital canal; it transmits the infraorbital artery, vein, and infraorbital nerve.-External links: *...
is V-shaped and extends to the roof of the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
, and the incisive foramina
Incisive foramen
The fossa incisiva is an opening in the bone of the oral hard palate where blood vessels and nerves may pass. There are four of these openings in the incisive fossa.-Formation:...
are medium to large in size. The zygomatic plate
Zygomatic plate
In rodent anatomy, the zygomatic plate is a bony plate derived from the flattened front part of the zygomatic arch . At the back, it connects to the front root of the zygomatic arch, and at the top it is connected to the rest of the skull via the antorbital bridge. It is part of the maxillary...
is at least moderately developed in this group, producing the V shape. The common ancestor to the Eumuroida were probably not specialized as burrowing animals, whereas the spalacid ancestor may have been.
Jansa and Weksler (2004) noted that the Eumuroid ancestor likely had hamster
Hamster
Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera....
-like (cricetid
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
) molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
s as opposed to mouse
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
-like molars (murid
Muridae
Muridae is the largest family of mammals. It contains over 600 species found naturally throughout Eurasia, Africa, and Australia. They have been introduced worldwide. The group includes true mice and rats, gerbils, and relatives....
). Essentially, the occlusal surface of the molars probably had two rows of cusps (cricetid) instead of three (murid).
Early fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
muroids
Muroidea
Muroidea is a large superfamily of rodents. It includes hamsters, gerbils, true mice and rats, and many other relatives. They occupy a vast variety of habitats on every continent except Antarctica. Some authorities have placed all members of this group into a single family, Muridae, due to...
such as cricetodontines represent a possible ancestor
Ancestor
An ancestor is a parent or the parent of an ancestor ....
to the Eumuroida. These rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s have the cricetid tooth, hence the name: cricetus = hamster
Hamster
Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera....
+ dont = tooth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
. The presence of these fossils in Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
is parsimonious
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
, because most families of eumuroids (except the Nesomyidae) have representatives in Asia. Steppan et al. (2004) suggested that the most recent common ancestor of the Eumuroida lived around the transition between the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
and Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
. This date only slightly precedes the first appearance of cricetodontines.
Taxonomy
- Family Calomyscidae
- Subfamily Calomyscinae (mouse-like hamsterMouse-like hamsterthumb|200px|rightthumb|200px|right|Mouse-like hamster using its tail for balance while standing on a branch .Mouse-like hamsters are a group of small rodents found in Syria, Azerbaijan, Iran, Turkmenistan, Afghanistan, and Pakistan...
s)
- Subfamily Calomyscinae (mouse-like hamster
- Family NesomyidaeNesomyidaeNesomyidae is a family of African rodents in the large and complex superfamily Muroidea. It includes several subfamilies, all of which are native to either continental Africa or to Madagascar...
- Subfamily Cricetomyinae (pouched rats and mice)
- Subfamily DendromurinaeDendromurinaeDendromurinae is a subfamily of rodents in the family Nesomyidae and superfamily Muroidea. The dendromurines are currently restricted to Africa, as is the case for all extant members of the family Nesomyidae. The authorship of the subfamily has been contributed to both Alston, 1876, and to G. M...
(African climbing mice, gerbil mice, fat mice and forest mice) - Subfamily Mystromyinae (white-tailed ratWhite-tailed RatThe white-tailed rat, Mystromys albicaudatus, also known as the white-tailed mouse, is the only member of the subfamily Mystromyinae in the family Nesomyidae...
) - Subfamily NesomyinaeNesomyinaeThe Malagasy rats and mice are the sole members of the subfamily Nesomyinae. These animals are the only native rodents of Madagascar, come in many shapes and sizes, and occupy a wide variety of ecological niches. There are nesomyines that resemble gerbils, rats, mice, voles, and even rabbits...
(Malagasy rats and mice) - Subfamily Petromyscinae (rock mice and the climbing swamp mouse)
- Family CricetidaeCricetidaeThe Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
- Subfamily ArvicolinaeArvicolinaeThe Arvicolinae are a subfamily of rodents that includes the voles, lemmings, and muskrats. They are most closely related to the other subfamilies in the Cricetidae . Some authorities place the subfamily Arvicolinae in the family Muridae along with all other members of the superfamily Muroidea...
(voleVoleA vole is a small rodent resembling a mouse but with a stouter body, a shorter hairy tail, a slightly rounder head, smaller ears and eyes, and differently formed molars . There are approximately 155 species of voles. They are sometimes known as meadow mice or field mice in North America...
s, lemmingLemmingLemmings are small rodents, usually found in or near the Arctic, in tundra biomes. They are subniveal animals, and together with voles and muskrats, they make up the subfamily Arvicolinae , which forms part of the largest mammal radiation by far, the superfamily Muroidea, which also includes rats,...
s and muskratMuskratThe muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...
) - Subfamily Cricetinae (true hamsterHamsterHamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera....
s) - Subfamily NeotominaeNeotominaeNeotominae is a subfamily of the family Cricetidae. It consists of four tribes, 16 genera, and many species of New World rats and mice, predominantly found in North America. Among them are the well-known deer mice, white-footed mice, packrats, and grasshopper mice.Neotomines are related to the...
(North American rats and mice) - Subfamily SigmodontinaeSigmodontinaeThe subfamily Sigmodontinae is one of the most diverse groups of mammals. It includes New World rats and mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the species count...
(New World rats and miceNew World rats and miceThe New World rats and mice are a group of related rodents found in North and South America. They are extremely diverse in appearance and ecology, ranging in from the tiny Baiomys to the large Kunsia...
) - Subfamily TylomyinaeTylomyinaeThe subfamily Tylomyinae consists of several species of New World rats and mice including the vesper and climbing rats. They are not as well known as their relatives in the subfamilies Sigmodontinae and Neotominae...
- Subfamily Arvicolinae
- Family MuridaeMuridaeMuridae is the largest family of mammals. It contains over 600 species found naturally throughout Eurasia, Africa, and Australia. They have been introduced worldwide. The group includes true mice and rats, gerbils, and relatives....
- Subfamily DeomyinaeDeomyinaeThe subfamily Deomyinae consists of four genera of mouse-like rodents that were placed in the subfamilies Murinae and Dendromurinae until very recently. They are sometimes called Acomyinae, particularly in references that predate the discovery that the link rat, Deomys ferugineus, is part of the...
(spiny mice, brush furred mice, link rat) - Subfamily Gerbillinae (gerbilGerbilA gerbil is a small mammal of the order Rodentia. Once known simply as "desert rats", the gerbil subfamily includes about 110 species of African, Indian, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats...
s, jirds and sand rats) - Subfamily Lophiomyinae (crested rat)
- Subfamily MurinaeMurinaeThe Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. This subfamily is larger than all mammal families except the Cricetidae and Muridae, and is larger than all mammal orders except the bats and the remainder of the...
(Old World ratRatRats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s and miceMouseA mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
including vlei ratVlei RatThe Southern African Vlei Rat is a species of rodent in the Otomys genus of the family Muridae.It is found in Lesotho, Mozambique, South Africa, Swaziland, and Zimbabwe....
s)
- Subfamily Deomyinae